1. Field of the Invention
The present invention relates to a liquid electrophotographic printer, and more particularly, to a transfer roller cleaning apparatus for cleaning the surface of a transfer roller which transfers a developed image formed on a photoreceptor medium to a printing sheet of paper.
2. Description of the Related Art
In an electrophotographic printer, a latent electrostatic image formed on a photoreceptor medium such as a photoreceptor drum or a photoreceptor belt is developed by using a developing solution having a toner mixed with a volatile liquid carrier, and the developed image is transferred onto a printing sheet of paper, thereby printing a desired image.
Referring to FIG. 1 schematically showing a conventional liquid electrophotographic color printer, a photoreceptor belt 110 is supported by a plurality of rollers 121, 122 and 123 and circulates along an endless track. The surface of the photoreceptor belt 110 is charged by a charging station 150 to a constant electric potential. Then, a latent electrostatic image is formed on the photoreceptor belt 110 by a laser scanning unit 130 for emitting laser beams according to image signals. The formed latent electrostatic image is developed by a development station 140 for supplying a developing solution. As shown in FIG. 1, in the case of a color printer, a plurality of laser scanning units 130 and development stations 140 corresponding to various colors are provided.
The liquid carrier contained in the developing solution sticking to the latent electrostatic image of the photoreceptor belt 110 is evaporated while passing an image drying station 160 and then only the dried toner remains.
Subsequently, while the photoreceptor belt 110 passes through between the roller 121 and a transfer roller 124, an image formed by the toner sticking to the photoreceptor belt 110 is transferred to a sheet 126 fed between the transfer roller 124 and a fixing roller 125 via the transfer roller 124, to then be printed. Thereafter, an electrostatic charge remaining in the photoreceptor belt 110 is removed by an erasure station 170.
Here, the toner image sticking to the transfer roller 124 is not completely transferred to the sheet 126 during the transfer procedure, and some toner sludge may remain in the transfer roller 124. The residual toner sludge or foreign matter sticking to the transfer roller 124 may contaminate the surface of the transfer roller 124 in repetitive printing procedures, thereby adversely affecting the printing quality of an image.